Circulating lipids have been proposed to influence the risk of breast, colorectal, and other common cancers, but results from conventional epidemiologic studies have been inconsistent.

Alicia Beeghly-Fadiel, PhD, Nikhil Khankari, PhD, Wei Zheng, MD, PhD, and colleagues in the Breast Cancer Association Consortium used Mendelian randomization analysis to evaluate associations between breast cancer risk and four genetically predicted lipid traits.

They used 162 genetic variants associated with high density lipoprotein-cholesterol (HDL-C), low density lipoprotein-cholesterol (LDL-C), triglycerides and total cholesterol to construct weighted genetic scores for 101,424 breast cancer cases and 80,253 controls. Increased genetically predicted HDL-C was associated with an increase in breast cancer risk. Associations with triglycerides and total cholesterol were inconsistent, and no association was observed for LDL-C.

The findings, reported in the International Journal of Epidemiology, suggest that high circulating HDL-C levels may increase breast cancer risk. The authors note that the findings are surprising given that increasing HDL-C is thought to be healthy, and they point to the need for additional research.

—Leigh MacMillan